Arsenal X2 today

So I was in my LGS picking up some ammo for my new Kel-tec PMR-30 when I saw what I think is a Arsenal sgl-21. I looked it over and realized its used and an Arsenal not a Fime group with a sticker of $900. Then I noticed some rust on the brake and that's where the negotiations started
Because it looks like someone shot some corrosive ammo in it and didn't clean the brake. After some wheel and dealing I ended up picking it up for $750 due to the brake not coming off and a little surface rust in the brake NO where else. Everything else including the bore looks new and hardly used.

So what do you guys think what model is it sgl 21 something?

My plan is to soak brake and then dump a few mags then try to remove the brake. Anyone have any experience with this?

Maybe heat it up with a hair dryer. Make sure the detent is pushed in. Stick one of the squeeze grip ends of a big pair of pliers through the hole in the brake and turn counter clockwise. (Not a left handed 14x1 thread). Also hot water desolves salts another possibility. Or take it to the range and heat it up then remove later. Just throwing some ideas out there. CLP should not hurt the finish. Hopes 9 will for sure though. Just my 2 cents. Except for the Hopes. That stuff will remove the finish in front of your eyes. I learned the hard way.